Wireless printing

Help please! I have for months had on/off problems with wireless printing. We are a family of five and use a mixture of ipad 2, ipad 3 and lap-top, all of which connect no problem to the router (TG582n). The printer (I have tried with an Epson XP412 and Brother (DCP - J152W) all connect to the router no problem and display that they are connected and print connection reports saying that they are connected. But the vast majority of the time, when I try to print (using Airprint and also the respective ipad app for respective printer), the printer cannot be found. But just occasionally, it can, and it works a treat!As you can tell, I'm no expert, but any advice or signposts would be greatly appreciated! Thank you.